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LEGEND
W2 — Second-Stage Heat
Y2 — Second-Stage Compressor
RS2 — Second Remote Sensor (Not Used)
RS+5 — +5 vdc for 2 Sensors
RS1 — Remote Sensor
RS GND — Ground for 2 Sensors
W1/O/B — First-Stage Heat or Reversing Valve
Y1 — First-Stage Compressor
G—Fan
W3/ECO — Third-Stage Heat or Economizer (Not Used)
CK1 — Dry Contact
CK2 — Dry Contact Ground
R—24 vac Transformer
C—24 vac Transformer Common
Fig. 2 — Thermostat Wiring
W2
TYPICAL
UNIT
L
C
G
Y1
E
O
W1
R
Y2
24 VAC COMMON
FAN RELAY
COMPRESSOR RELAY
1st STAGE HEAT CIRCUIT
24 VAC RETURN
2nd STAGE HEAT CIRCUIT
W2
Y2
R
W1
Y1
G
C
THERMOSTAT
B
O
Fig.3—Typical Wiring (Single-Stage Cooling Units)
W2
TYPICAL
UNIT
L
C
G
Y1
E
O
W1
R
Y2
24 VAC COMMON
FAN RELAY
COMPRESSOR RELAY
1st STAGE HEAT CIRCUIT
24 VAC RETURN
2nd STAGE COMPRESSOR RELAY
2nd STAGE HEAT CIRCUIT
W2
Y2
R
W1
Y1
G
C
THERMOSTAT
B
O
Fig.4—Typical Wiring (Two-Stage Cooling Units)
Table 1 — Thermostat Wiring Terminations
EXISTING
WIRE
DESIGNATION
FUNCTION
TERMINAL
CONNECTION
GorF Fan G
Y1, Y, or C Cooling Y1
W1, W, or H Heating W1/O/B
Rh, R, M, Vr, or A Power (24 v) R
C Common C*
O/B Reversing Valve W1/O/B†
Y2 Second Stage Cooling Y2*
W2 Second Stage Heating W2*
RS+5 Remote Sensor (5 vdc) RS+5
RS Remote Sensor Signal RS1
RS G Remote Sensor Ground RS GND
CK1 Dry Contact Switch CK1
CK2 Dry Contact Ground CK2
*Terminals C, Y2, and W2 may not be used in all applications.
†Used on Heat Pump applications only.
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